更新：我希望在复选框的帮助下，将已故的学生提升到下一学期。对于那些检查过的学生，我希望更新学期。但学生学期增加2而不是1。从sem 1传出的学生被提升为sem 3而不是2。
以下是我正在使用的更新代码：
$con=mysqli_connect("$host", "$username", "$password", "$db_name");
if(mysqli_connect_errno($con))
{
echo 'Failed to connect';
}
else
{ echo 'Connection established';
echo "<BR><BR>";
}
if(isset($_POST["submit"])){
//echo 'hello submit<br>';
if($_POST['checkbox']){
//echo 'hello checkbox<br>';
for($i = 0; $i < count($_POST['checkbox']); $i++)
{
echo count($_POST['checkbox']);
echo '<br>';
$temp = implode(',', array_fill(0, count($_POST['checkbox']),'?'));
echo $temp;
echo '<br>';
$query = "UPDATE students_in_courses
SET
semester = semester + 1
WHERE
roll_number IN ($temp) ";
$types = str_repeat('s', count($_POST['checkbox']));
$prepare = $con-> prepare($query);
$prepare-> bind_param($types, ...$_POST['checkbox']);
$prepare->execute();
if ($prepare->execute()) {
echo 'The student\'s records have been updated.';
} else {
echo 'There was a problem updating the student\'s records. <br>';
}
$prepare->close();
}
}
}
$sql="SELECT * FROM students_in_courses where course_name = 'B.Ed' ";
$result=mysqli_query($con,$sql);
if (mysqli_num_rows($result)==0)
{
echo 'No records found';
}
else
{
echo '<form name="frmactive" method="post" action="">';
echo '<table>';
echo '<tr><td colspan="4"><strong>Update multiple rows in mysql with checkbox</strong></td></tr>';
echo '<tr><td></td><td><strong>Roll Number</strong></td>';
echo '<td><strong>Course</strong></td>';
echo '<td><strong>Semester</strong></td>';
echo '<td><strong>Year</strong></td></tr>';
while($rows = mysqli_fetch_array($result))
{
echo '<tr><td><input name="checkbox[]" type="checkbox" id="checkbox[]" value = "'.$rows[0].'"></td>';
echo '<td>'.$rows[0].'</td>';
echo '<td>'.$rows[1].'</td>';
echo '<td>'.$rows[2].'</td>';
echo '<td>'.$rows[3].'</td></tr>';
}
echo '<tr><td><input type = "submit" name = "submit" value = "submit">';
echo '</table></form>';
}
?>
<html>
<body>
</body>
</html>
答案 0 :(得分：0)
我假设您使用了POST方法：
if(isset($_POST['submit'])){
if(!empty($_POST['checkbox'])) {
foreach($_POST['checkbox'] as $value){
echo "value : ".$value; // Here you get value of checked checkbox.
// ----- Now Here Execute query to update Semester ------
}
}
}
答案 1 :(得分：0)
好的，试试吧。你有正确的想法，但我们将专门告诉查询要更新哪一行。否则，查询将只为每一行添加一个学期。
此外，您应该使用参数化查询。我不使用mysqli所以我研究了它，我认为我的代码是正确的。我没有测试过。参数化您的查询将阻止sql注入。
给它一个镜头，它应该工作：
if(isset($_POST["submit"])){
if($_POST['update']){ //<--Check to make sure that update has values in it.
for($i = 0; $i < count($_POST['update']); $i++){
//Make sure the table name is correct.
$query = "UPDATE students_in_course
SET
semester = semester + 1
WHERE
roll_number = ? ";
//We are going to use paramterized query stucture. This
//will prevent sql injection.
$prepare = $con->prepare($query);
$prepare->bind_param('s', $_POST['update'][$i]);
$prepare->execute();
if ($prepare->execute()) {
echo 'Student #' . $_POST['update'][$i] . ' was successfully updated. <br>';
} else {
echo 'There was a problem inserting student # ' . $_POST['update'][$i] . ' into your database. <br>';
}
$prepare->close();
}
}
}
上面的方法循环检查了每个学生。在每次迭代中，它为该个别学生单独查询。
更高级的方法是使用$ _POST ['update']数组直接进行一次查询，以使用WHERE IN子句扩展查询。这将更新仅使用一个查询选择的所有学生。
像这样：
if(isset($_POST["submit"])){
if($_POST['update']){ //<--Check to make sure that update has values in it.
$clause = implode(',', array_fill(0, count($_POST['update']), '?')); //create 3 question marks
//Make sure the table name is correct.
$query = "UPDATE students_in_course
SET
semester = semester + 1
WHERE
roll_number IN ($clause) ";
$types = str_repeat('s', count($_POST['update'])); //create 3 "s" or for bind_param.
$prepare = $con->prepare($query);
$prepare->bind_param($types, ...$_POST['update']);
$prepare->execute();
if ($prepare->execute()) {
echo 'The student\'s records have been updated.';
} else {
echo 'There was a problem updating the student\'s records. <br>';
}
$prepare->close();
}
}
我用这个页面用mysqli研究预备语句。此页面上有大量信息和示例。你一定要看看它。
https://websitebeaver.com/prepared-statements-in-php-mysqli-to-prevent-sql-injection